Automatic telephone system



Patented Oct. 25, 1927.

UNITED STATES PATENT OFFICE.

JOHN E. GARDNER, OF CHICAGO, AND JOHN I. BELLAM'Y, .OF BEOO'KIIELD, ILLINOIS, ASSIGNORS, BY MESN'E ASSIGNMENTS, T0 AUTOMATIC ELECTRIC INC., 101 OHIGAGO, ILLINOIS, A CORPORATION OF DELAWARE.

AUTOMATIC TELEPHONE SYSTEM Original ap lication filed October ,9, 1922, Serial No. 593,413., new, Iatent No. 1,610,438, dated. December j 14, 1926. Divided and this application filed September 23, 1926. :Serial No. 137,217.

The present invention relates in general to automatic telephone systems, but is more particularly concerned with systems of this character employing partylines; and the general object of the invention is to provide a novel and improved party line system in which revertive calls may be made, that is, calls from one subscriber on one line to another subscriber on the same line, in the same manner as ordinary calls by dialling the regular directory number of the .desired party.

More particularly it is the object of the invention to provide automatic ringing on revertive calls. To explain more fully, .a subscriber desiring to call another party on his own line dials the regular directory number of that party and the connection is established in the usual manner through the regular trunking system. -Responsive .to the establishment of the connection, automatic ringing equipment is placed in operation and the desired party is signalled in the same manner as if-an ordinary call were in progress. When the called party responds the ringing current is disconnected and the talking circuits are established. An additional object of the invention .is to change the .circuits of the connector switches which are used to extend connections to party lines, so that on revertive ,calls the response of the wanted subscriber brings about the release of the connector switch and selector switches, talking battery being fed to both calling and called subscribers from the windings of the line relay or the first selector. V

Another object of the invention is to give the telling subscriber when he makes a re rerlive call the regular ringing induction to inform him when the desired connection is established.

All the features pointed out above are (claimed broadly in the parent application, Serial No 593,413, now Patent No. 1,610,438 :ot'which this application is a division. In this divisional. application a particular modification will be disclosed and claimed.

Refi rring now to the drawing, there is shown by means of the usual schematic cir- .cuit diagrams, sufiicient of the apparatus of the system to enable the invention to be clearly described and understood.

be described in detail.

The substation A is similar to the usual automatic type. However, its circuits have been modified so as to enable the same to be used with the present invention. fWhile only the circuits of one substation on the party line have been shown herein, it will bev understood that the other substation A thereon, the ringer of which has been indicated, will be similar to the substation A. The party line terminates at the exchange an individual line or trunk selecting switch I: I i

v The line switch 0 is of the usual rotary type whose-wipers'have no normal position, always standing, when idle, with its wipers in association with the bank contacts of the trunk line last used- This linel switch C, in common with a plurality of other line switches, has access to trunk lines leading to first selector switches.

I The first selectors have access to trunk lines leading to second selectors and the second selectors in turn have access to trunk lines extending to connector switches, one

of these trunk lines being the trunk line shown in the drawings extending to the connectorH.

a The connector H is of the usual 'Strow-ger vertical and rotary type and has access to party lines, one of these bein the one comprising conductors 2.88and 289 extending-to substations A" andA'. Its circuit arrangements form a particular part of this "invention and will be described in detail hereinafter;

In order to enable each of two parties on the same line tofbe selectively signalled, harmonic ringing is employed. Two groups of connectors have access to one party line and each group has a different frequency of ringing current associated with it. To signal the desired party on the party line it is only necessary to select a connect o-r. in the particular group. This is the scheme of harmonicringing ordinarily used in automatic systems.

The operation of invention will now will be assumed that some subscriber desires to call the subscriber at substation A. To accomplish this result the subscriber at the calling substation will remove his receiver and operate his calling device for the For. this purpose it the usual manner.

digits of the directory number of the sub scriber at substation When the receiver is removed at the calling substation,-the llne described. It will be assumed that the connection is extendedto the connectorH over the trunk line comprising conductors 88- 90, inclusive. The line relay202of this switch. operates to close the circuit of the slow actingrelease relay 203. Upon operating, relay 203 prepares the operating circuits oftheconnector H at'armature- 232 and at armature 231Iplacesground upon the release trunk coi1ductor89 to establish the usual holding circuit for the previously operated'switches, 1

In response to the first operation of the calling device at the calling substationt he vertical magnet 213 is operatedunder control of the line relay202 to raise the switch wipers 260262, inclusive, step by step, until thewipers are placed oppositethe proper level of bank contacts. Slow acting relay 20a is energized in series with the vertical magnet and operated to maintain its armature attracted throughout the vertical 1novement of the switch, thereby maintaining the vertical magnet circuit closed when the off normal springs are shifted, which operation occurs upon thefirst vertical step of the switch. Upon deenergizing at the end of the vertical movement, the slow acting relay 204 transfers the impulsingcircuit to. the rotary magnet 214.

hen the calling device at the calling substation is operated in accordance with thenext and final digit in the desired number the rotary magnet 21a is operated under control of the line relay 202 and operates to advance the switch wipers into engagement with the bank contact set comprising contacts 270-272, inclusive, associated with the line of the substation A. The relays 207 and 208 are energized and function in "a manner to be described hereinafter.

1 Assuming that the desired line is idle at this time, the switching relay 209 is enerized in series with the switching 'l elay 275 of the line switch 0 operates to relay 275.

disconnect thejline of the called substation from its normal battery and ground connections in the line switch. Relay 209; upon operating, establishes a locking circuit for itself at armature253 and at armatures 251 and 255 prepares the signaling circuit.

' Upon the deenergization of relay 208, which was energized in multiple with rotary magnet 21th, the signaling circuit is closed This circuit extends from the generator lead 290 by way of back contact and armature 221,through the upper winding of the ring out off relay 205, back contact and armature 236, back contact andarmature 246, front contact and armature 251, wiper 260, bank contact 270, overthe line, conductor 288, lower right hand winding of the ringer, condenser, lower left hand winding of the ringer, springs of the calling device, line connectors, only the bells of the substation A respond. lVhen the receiver is removed, ring cut-off relay 206 is energized over the called line loop and operates to establish a locking circuit for itself at arn'iature 238, and to disconnect the ringing current and to complete the talking. circuit at armatures 236 and 239. The back bridge relay 201.js energized over the called line and operates to reverse the connection of the line relay 202 'with regard to the incoming trunk conductors for supervisory or metering purposes'in the usual manner.

The two subscribers may now engage in conversation, and when the conversation is terminated, the release of the connection takes place in the usual manner.

If the line of the substation A is busy when the wipers of the connector H are brought into engagement with the bank contacts 270272, inclusive, the busy signal is given to the calling subscriber by the operation of thetest relay 206 in the well known manner.

It will now be assumed that the subscriber at substation A" desires to call the other party at substation A on his own line. In this case the operation is substantially the same as before described. That is, the line switch C, and a first and a second selector are operated. to seize a connector such as the contacts 270-272, inclusive, the relays 207 and 208 operate conjoint-1y to bring about a reduction of the potential on the test contact 271 inorder toenergize the switching'relay 209. This operation is as follows: During the rotary movement of the switch, relay 207 is operated in multiple with magnet 214,

andrelay 208 is operated, its circuit including armature 245. At the end of the vertiamasse- Jalmovement, these relays d'eenergize in succe'ssion, relay 20S maintaining its: armatures attracted a short time after its circuit is opened by the release of relay 207. Thus the potential on the release conductor 89 extending throiirgh the preceding operated switches and connected to conductor 36 is reduced suiliciently' to causerelay 209 to energize. Upon operating, relay 209 establishes alocki ng circuit for itself and prepares points in the signallingcircuit'.

Since the: receiver is removed at substation 9;, relay 200 is energized over the calling line loop and operates to'establish a looking circuit-tor itseli at armature 24.0. Other results of this en rgization are that at armature 221 relay 200 prepares certain points in the signalling circuit, at armature 222 disconnec-ts ground from the wiper 262 and connects it to'conductor 89, at armature 223 places ground upon the conductor 256, at armature 22% opens a point in the release nag-net circuit. and at armatures 220 and 226 disconnects the line relay 202' from the calling line. Relays 202 and 203 deenergize, which operation effects no particular results at the present time.v Still another result of the energization of relay 200 is. that a circuit is prepared for the lower winding of the ring cut oil relay-205.: Upon the deenergiza tion of relay 208, the ringing circuit is completed and also the circuit ofthe lower wind:-

ot relay 205 at armatures 246'and 249, respectively. The ringing circuit may be traced from the generator lead 290' through the alternating currentrelays 211 and 210 in series, armature 221 and its front contacts, to wipers 260 and 262, thence over the line conductors 288- and 289 in parallel through the lower windings of the bell coils 28 5 and 284, through the condenser, and through the upper windings of the bell coils to ground by way of switch-hook springs 282. Thus the ringer at substation A is actuated over a simplex circuit which includes the two line conductors ,in parallel. As this circuit is opened at substation A by the receiver bein ofi the switchhook, no ringing current flows through the ringer at substation A. It will be remembered that when the ringing circuit is completed a circuit is also closed for the lower winding of'the ring cut-off relay 205.- However, the ring cut-off relay does not energize at this time due to the factthat it is slow to operate and that this circuit is immediately opened at armature 240, by the energization of alternating current relay 211. The: alternating current relay 210 in series with relay 211 is marginal and is not operated in series with the ringer at substation A. During the time the interrupter relay 29 :1 1s 1n operated position, rlngmg current "from the 16 cycle generator 1s supplied to the line of the called substation in-orderto/ actuate the ringer thereat. During the silent. period, when the relay. 294 is deenergized, the 75 cycle generator is connected over the ringing circuit. The ringers at thesubstationsA and A are adapted not torespond to this frequency and are therefore not actuated. However,.the alternating current relay 211 is maintained energized.-

When the subscriber at substationArespends by: removing his receiver, the previously traced simplex circuit is opened by the operation-of the switchhook, and" the alternating current relay-211 deenergizes and completes the circuit of the ring outoif'relay 205. Upon operating, relay 205 establishes a locking circuit for itselfat armature 238, opens'the ringing circuit'at armatures 236-and239, and at armature 237 removes ground from the release trunk conductor 89 and also opens the locking circuit of the relay 200; The -disconnecti'on of ground from the release trunk conductor 89 and the deenergization of the relay 200 bring about the release of the connection in the well: known manner. The circuit of release magnet 212 is clos ed at armature 224:, and the circuits of relays 205 and 209 .are opened by the removal of ground from the holding conductor atarmature 223. As the receivers atthe.substations?! and A on the calling line are now removed the lineswit-ch C will operate to seize the selector usedin the preceding connection or another selector. Talking battery is. now supplied to the subscribers from the line relay or" the seized select-or. The connection comprising the switches C and the seized selector is released when both. receivers are replaced on the p arty line i Reconsidering the previous connection, it

will now be assumedthat the subscriber at substation A. did not respond and that the subscriber at substation A replaces his re 'ceiver. Responsive; to the latter operation,

the ringer at substation A is included in the simplex ringing circuit andthe imped ance of the circuit is accordingly decreased thus allowing a greater amount of current to flow through the marginal alternating current relay 210. which immediately energizes ,and'close's the circuit of the'ring cutoil relay 205 The energization of the ring cut-off relay 205 bring about the release of the connection in the same manner as has beenbefore described.

It will be seen that by the use oi? the system shown, it is possible to make a revert-ive call back to a desired subscriber" on the same line as the calling one in the same manner as if an ordinary call were being made to another: subscriber and in the case of this revertive call: all the switches are released when an answer is obta ned with the exception of the line switch and the v first selector. thereby materially reducing a series of selector switches and a connector switch under the control of asubscriber at one of the stations. on one of said lines for extending aconnection to another station on the-same line or to a station on another line, means in said connector switch operative when connectionis extended-to said same line for applying signalling current over a simplex circuit to signal the desired station, and means in said connector operative when connection is made with another of said lines for applying said signalling current over a series" circuit to signal the desired substation on the called line.

2. In a telephone system, telephone lines, a plurality of stations on each of said lines, a series of selector switches and a connector switch under the control of a subscriber at one of the stations on one of said lines for extending a connection to another station on the same line or to a station on another line, meansin said connector switch operative when connection is extended to said same line for applying signalling current over a simplex circuit to signal the desired station, means in'said connector oper ative when connection is made'with another of said lines for applying said signalling current over a series circuit to signal the desired substation on the called line, and means responsive to the removal of the receiver at the called substation in either con nection to disconnect said ringing current.

3. In a telephone system, telephone lines, a plurality. of stations on each of said lines, a series of selector switches and a connector switch under the control of a subscriber at one of the stations on one of said lines for extending a connection to another station on the same line or to astation on another line, a relay in said connector switch energized over the called line loop in case the called line is the calling line, and means controlled by the said relay ior applying signalling current to the called line over a simplex circuit. i

4. In a telephone system, telephone lines, a plurality of stations on each of said lines, a series of selector switches and a connector switch under the control of a subscriber at one of the stations on one of said lines for extending a connection to another station on the same line or to a station on another line, a relay in said connector switch enerpointed out in the appended gized over the called line loop in case the called line isthe calling line, means cone trolled by the said relay for applying signalling current to the called line over a simplex circuit, said relay remaining deenergized when connection is made withanother of said lines whereby signalling currentis applied to the last mentioned line over a series circuit. 1

5. In a telephone system, a telephone line having a plurality of stations. thereon, an automatic switch controlled from'acalling one of said stations for extending a connectionto said line, a source of ringing current, and means responsive to the establishment of said connection for applying said source to 7 said line overa simplex circuit.

I6. In a telephone system, a telephone line having a plurality" of stations thereon, an automatic switch controlled from a calling one'of said stations for extending a connection to said line, a source of ringing current, means responsive to the establishment of said connection for applying said source to said line over a simplex circuit, and means controlled over sald simplex c1rcu1t for CllS connecting said ringing current responsive to tlle'lfllllOVfll of the receiver at the called substation. a

7;In a telephone system, a party line, a

calling and a called station on said line, an

automatic switch, means controlled from said calling station for operating said-switch to connect withsaid line, means in said switch for automatically signalling the called station, a first and a second ring outoff relay in said switch said first relay being responsive to the replacement of the receiver at the calling station to interrupt the signalling ot' the called station, and said second relay being responsive to the removal of'the receiver at the called station to interrupt the signalling of the called station.

I 8. In a; telephone system, a party line, a calling and a called station on said line, an automatic switch, means controlled from said calling station for operating said switch to connect with said line, means in said switch for automatically signalling the called station, a first and a second ring outoff relay in said switch said first relay being responsive to the replacement of the receiver at'the calling station to interrupt the signal ling of the called station and to effect the release of said switch, and said secondrelay being responsive to the removal of the receiver at the called station to interrupt the signalling of the called station and to effect the release of said switch.

9. In a telephonesystem, a party line, a

second line, a calling station on said party line, an automatic connector switch, means controlled from said calling station for operating said switch to connectwith either of said lines, signalling means in said switch, a

first and a second ring cut-off relay in said switch, and means for connecting said sig nailing means to the line connected with via either of said ring cut-off relays, depending on whether the line connected with is said party line or said second line.

10. In a telephone system, a line, means for extending a connection to said line, means for applying signalling current to said line, means for increasing said current, means for decreasing said current, I and means responsive to either a decrease of said current or an increase in said current for disconnecting said current from said line.

11. In a telephone system, a line, an automatic switch. means for operating said switch to extend a connection to said line, means in said switch for applying signalling current to said line. and means responsive either'to a decrease or an increase in said current for releasing said switch.

12. In a telephone system, a line, an automatic switch, means for operating said switch to extend a connection to said line, means in said switch for applying signalling current tosaid line, a ring-out-ofl relay in said switch for disconnecting said current from said line, and means responsive either to a decrease or an increase in said current for controlling said relay.

13. In a telephone system, a line, means for extending a connection to said line, a source of signalling current, a relay, means for intermittently connecting said source in series with said relay to said line to periodi-' rent, a signal on said line responsive to current from one of said sources, relay responsive to current from both of said sources, and means for alternately connecting said sources to said line to operate said signal intermittently and to operate said relay continuously.

In witness whereof, I hereunto subscribe my name this 14th day of September, A. D. 1926.

JOHN E. GARDNER.

In witness whereof, I hereunto subscribe my name this 14th day of September, A, D.

JOHN I. BELLAMY. 

